The Contractor shall supply, install, test, connect and commission, in the main L.V. Electrical room, an Automatic Power Factor Correction Panel, designated PFCP, of kVAr rating as called for and as indicated in the single line power distribution schematic drawing and in the load schedules for respective Main Distribution Board, MDB.
Unless stated otherwise, the PFCP shall not form an integral part of the Main Distribution Board.
The PFCP shall comprise a robust enclosure equipped with and complete with main incoming isolating switch, an electronic power factor regulator/controller, power factor improvement capacitors, contactors, fuses and any other components and accessories deemed necessary for a high quality, high-performance, reliable and safe power factor correction equipment.
The components of PFCP shall be selected and designed to ensure that the power factor of the system is maintained at a minimum value of 0.9 lag, or a value stipulated by DEWA, for all loads up to full load of the system. In addition, each PFCP shall be equipped with harmonic suppression reactors.
1. GENERAL
In general the PFCP shall conform to the following specifications and requirements:
1.1. The PFCP shall be factory built and shall be of modular cubicle pattern, floor
mounted, free standing, air-insulated, totally enclosed type, and shall, in addition, be corrosion, dust and damp proof to comply with the requirements of BS 60439 - 1:1999. Minimum degree of protection shall be IP 54.
1.2. The PFCP shall be constructed of highest-quality corrosion-resistant sheet
steel of adequate thickness, coated with an approved compound to provide excellent resistance against scratches and corrosion.
1.3. The PFCP shall be designed for total front access, and provision shall be made
for bottom/top entry for the main incoming cable and shall be complete with cable box, cable gland, lug, clamps etc. The PFCP shall be of suitable design to facilitate ease of cabling, maintenance, inspection and testing, and shall ensure maximum safety to operators, and to maintenance and testing personnel.
SPECIFICATIONS ELEC/SPEC.16411.
File: ELECSPEC16411.doc
Low Voltage Automatic Power Factor Correction Panel
Page 2 of 3
2. POWER FACTOR CORRECTION CAPACITORS.
2.1. Highly reliable low-loss (0.5 watts per kVAr) capacitors with self-healing
properties shall be used in the system.
2.2. The capacitors shall be environmentally acceptable using non-toxic
impregnants.
2.3. Each step shall be designed for 25/50 kVAr rating or as specified in the
distribution schematic drawing and load schedule/s for main distribution board/s.
2.4. All capacitors shall be derated to give design capacitance at 50 deg. C.
2.5. Each capacitor unit shall comprise requisite number of individual capacitor
elements. These elements shall be manufactured from impregnated metallized polypropylene or metallized paper and plastic film and have self-healing property. Each unit shall be fitted with a thermal protection device.
2.6. The safety protection system shall incorporate a fail-safe device for each
capacitor element.
2.7. Suitable discharge resistors shall be provided to ensure capacitor terminal
voltage shall be reduced to 50 volts in one minute after switching off.
2.8. All capacitors used in the system shall be of 600/1000 V insulation grade and
shall comply with the requirements, including latest amendments, of BS 1650:1971, IEC 831.
2.9. All capacitors shall be designed to withstand the following overloads:
Overload tolerance : 6-7 % permanently.
: 15 % 8 hours per day.
3. POWER FACTOR REGULATOR/CONTROL GEAR.
3.1. The function of the Regulator/Control gear shall be to monitor the network
reactive power and to achieve the required power factor by switching ON and OFF capacitor steps.
The Regulator/Control gear shall be microprocessor controlled, of compact design and insensitive to harmonics.
3.2. The equipment shall incorporate a special fast acting soft switching contactor
arrangement to minimize the adverse affects of high inrush currents and system disturbances caused by capacitor switching. Each kVAr step shall be controlled by two contactors switching in cascade. These contactors shall incorporate a pre-connection resistor system which reduces to a minimum the effect of current inrush. 100 A circuit fuses shall be installed to protect each 50 kVAr capacitor step and its associated control gear.
3.3. The Regulator/Control gear shall be designed and equipped with components
to provide the following features and facilities :
-- Adjustment of power factor setting from 0.7 lag to 0.9 lead.
-- Switching time between steps from 1 to 100 seconds.
-- No-volt release which instantly disconnects the automatic capacitor banks in the event of mains supply failure. With the return of mains voltage the capacitor banks shall be switched ON after 90 seconds. This feature shall be available for both AUTO and MANUAL operations.
-- Facility for Automatic and Manual operation.
File: ELECSPEC16411.doc
Low Voltage Automatic Power Factor Correction Panel
Page 3 of 3 SPECIFICATIONS ELEC/SPEC.16411.
-- LED indication of capacitive and inductive load and the number of
steps energized.
-- Automatic adjustment to changes in network frequency.
-- ON/OFF/AUTO switches with multistage switching facility
-- The Regulator/ Control gear shall be equipped with the following:
(i) 1 No. digital power factor meter covering a scale 0.7 lead-1-0.7
lagging.
(ii) Fault indicator to give alarm when the selected power factor
value is not reached within a period of 5 minutes, and in the event of mains supply failure.
4. MAIN INCOMING ISOLATOR/LOAD BREAK-SWITCH.
4.1. These shall be complete with effective arc splitting plates and self-cleaning
contacts and shall be designed for positive opening and manual operation, all in compliance with the requirements of BS EN 60947 - 3 : 1999.
4.2. The main incoming isolator/load break switch shall be of 600/1000 V
insulation grade designed and rated for the required capacitive switching duty and rated impulse withstand voltage of 12 kV.
5. CONTACTORS.
5.1. The Contactors shall be designed to withstand large transient current peaks at
high frequency of several kHz, which could occur during switching of capacitor banks. The manufacturer shall submit calculations for the largest peak current the proposed contactor will be able to make.
5.2. The Contactors shall have an electrical life time of 100,000 operations, and shall
be rated at 1.5 times normal rated current of capacitor banks.
5.3. The Contactors shall be designed and constructed to comply with the
requirements, including latest amendments, of BS EN 60947 - 4 - 1:2001.
6. HBC FUSES.
All low voltage fuses shall be current-limiting types of modern industrial design having
high breaking capacity to comply with the requirements of BS 88, BS EN 60269.
SPECIFICATIONS ELEC/SPEC.16426.
File: ELECSPEC16426.doc
Low Voltage Electrical Swichgear Main, Sub-Main and Final Distribution Board, Isolators and Load Break Switches
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